The present invention relates to a liquid crystal display, and more particularly to an improved liquid crystal display apparatus and method for checking the joining accuracy thereof
Conventionally, a liquid crystal display apparatus comprises a panel, a drive circuit and a control circuit. The pixels on the panel are driven by the drive circuit and the control circuit is designed to manipulate the drive circuit to control images displayed on the panel. In a liquid crystal display apparatus, the drive circuit is generally set on tape carrier packages (TCP) and the control circuit is laid out on a control circuit board. The TCP is coupled to the panel and the control circuit is coupled to the TCP, wherein the pins on the control circuit are constrained in a predetermined ring to correspond with pins on the TCP to maintain the display quality of the liquid crystal apparatus. Therefore, there is a need to check the joining accuracy of the pins to ensure the quality of the LCD. FIG. 1 shows the conventional method for checking joining accuracy of the pins on the control circuit board and the LCD panel of an LCD apparatus. TCP 1 is coupled to the control circuit 2, and it is difficult to observe the pins 3 on the control circuit 2 because TCP 1 blocks them. One way to check the joining accuracy of the pins is to cut a detection window 5 along the edge of TCP 1 to expose one pin 3 on the control circuit 2 for comparison with the corresponding pin 4 on TCP. All of the pins 3 and 4 are parallel and the pins 3 on the control circuit are designed to correspond with the pins 4 on TCP. If the exposed pin 3 in the detection window 5 is joined to the corresponding pin 4 approximately, the rest of pins match as well.
Conventionally, the pins 3 on the control circuit are joined to the pins 4 on TCP with solder. However, anisotropic conductive film (ACF) has become popular for joining the pins. When the anisotropic conductive film (ACF) is used to join the pins 3 on the control circuit to the pins 4 on TCP, the adhesive resins that are squeezes out will block the observation through the detection window 5. Therefore, it is not easy to check the joining accuracy of the pins when the anisotropic conductive film is chosen to join the pins 3 and 4.
An object of the present invention is to provide a liquid crystal display apparatus to easily check the joining accuracy of the pins on the control circuit board and the LCD panel.
Another object of the present invention is to provide a method for checking the joining accuracy of the pins on the control circuit board and the LCD panel by measuring the electric resistance between the pins thereon.
To achieve these advantages, a liquid crystal display (LCD) apparatus comprises an LCD panel a printed circuit board and a package unit coupled to the LCD panel. On the printed circuit board, there is a plurality of first pins, a first check pad and a second pad thereon, wherein at least one first pin is electrically connected to the first check pad and at least another first pin is electrically connected to the second check pad. There is a plurality of is second pins on the package unit, wherein the second pins join the first pins on the printed circuit board correspondingly to connect the first pins electrically.
In another aspect of the present invention provides a method for checking assembly accuracy of the pins on an LCD apparatus comprising the steps of:
providing a first check pad and a second check pad on the printed circuit board;
connecting at least one first pin to the first check pad;
connecting at least another first pin to the second check pad; and
measuring electric resistance between the first and the second pad to detect the electric resistance between the first and second pins.
According to another aspect of the present invention, the package unit is a tape carrier package (TCP) and the package unit further comprises a driving circuit thereon for driving the LCD panel. The printed circuit board further comprises a control circuit thereon for controlling the driving circuit. The first pins on the printed circuit board can be joined with the second pins on the package unit by anisotropic conductive film ACF or solder.